MXPA06007502A

MXPA06007502A - Process for conditioning azo pigments.

Info

Publication number: MXPA06007502A
Application number: MXPA06007502A
Authority: MX
Inventors: Edward H Sung; George H Robertson; Humberto A Velasquez
Original assignee: Sun Chemical Corp
Priority date: 2003-12-31
Filing date: 2004-12-29
Publication date: 2007-04-17
Also published as: CA2552378A1; WO2005065298A2; US7019121B2; WO2005065298A3; EP1709388A2; US20050139128A1

Abstract

A process for conditioning azo pigment with surfactants of ethoxylate alkyl phenols in the presence of a strong alkali in the aqueous condition.

Description

PROCESS FOR CONDITIONING AZO-COLORANTS FIELD OF THE INVENTION This invention relates to the conditioning of azo-dyes.

BACKGROUND OF THE INVENTION Organic azo-dyes have been widely used in the paint industry based on a range of color display and relatively low cost. However, organic dyes in the form initially obtained after chemical synthesis, ie, unpurified dyes, are generally unsuitable for immediate use as colorants. Most unpurified dyes have a small particle size and have a transparent color, resulting in poor color stability. These dyes therefore often require additional treatment during preparation to modify the particle size and particle conformation and / or crystal structure to increase opacity and / or improve color stability. These methods include heating the unpurified dyes in the presence of a solvent or in an aqueous medium at a higher temperature and, often rapidly, placing the unpurified dye in a pressure reactor until the desired particle size is reached. U.S. Patent No. 4,476,052 discloses a process for the preparation of azo-dyes by heating the dye obtained after coupling in an organic solvent at 80-180 ° C. The addition of this organic solvent improves the opacity for the dye, however, the flammability of the solvent and its recovery not only increases the cost of processing but also causes that the manipulation of the dye is inconvenient and a potential safety risk in the majority of traditional azo plants. Thus, there is a need for an efficient and effective process for preparing an azo dye by which the azo dye has good color stability, large particle size, and opacity without requiring a flammable solvent component.

SUMMARY OF THE INVENTION It has now been found that the above objectives can be obtained by employing a process for conditioning an azo-dye with ethoxylated alkylphenol surfactants in the presence of a strong alkali in aqueous solution. The present invention also provides a process for conditioning an azo dye having improved dispersibility and opacity comprising: (a) preparing an azo dye through a conventional coupling technique in water; (b) the treatment of an azo-dye suspension with ethoxylated alkylphenol surfactants in the presence of a strong alkali; (c) heating the aqueous suspension to a temperature between about 95-100 ° C; and (d) the isolation of the conditioned azo-dye. Other objects and advantages of the present invention will become apparent from the following description and appended claims.

DETAILED DESCRIPTION OF THE INVENTION The present invention generally provides a process for conditioning an azo dye in which the dye is treated with ethoxylated alkylphenol surfactants in the presence of a strong alkali in an aqueous condition. The method achieves improved opacity in the dye without the additional need for processing. Organic colorants suitable for use in the present invention include, but are not limited to: naphthol reds, yellows and monoazo oranges, and yellow and diaryluro oranges. Suitable surfactants for use in the present invention include, but are not limited to: ethoxylated alkylphenols such as, for example, nonylphenoxy poly (ethyleneoxy) ethanol and octylphenoxy poly (ethyleneoxy) ethanol. The present invention also includes a strong alkali suitable for use in the present invention such as, for example, in a way: sodium hydroxide, potassium hydroxide, lithium hydroxide and ammonium hydroxide. It is preferred that the strong alkali be sodium hydroxide. The amount of strong alkali is essential for the growth of azo-dyes particles, which correlates directly with the opacity. In one embodiment of the present invention, at least two to ten mole equivalents of alkali formalin dye are added during the conditioning process. It is preferred to add during the conditioning process of the present invention from about four to six mole equivalents of alkali per mole of dye. The colorant may be added during the conditioning process of the present invention in an amount of about 2-12% by weight based on the colorant. It is preferred to add about 3-10% by weight of the surfactant during the conditioning process of the present invention. In the past, when the conventional conditioning of a dye in aqueous solution was carried out, the opacity of the resulting product was limited by the boiling temperature of the water and therefore a pressure reactor was often required in order to achieve an opacity convenient. It has now been found that an azo dyes can be opacified by treating the azo dye with ethoxylated alkylphenol surfactants in the presence of strong alkali in aqueous condition without using a pressure reactor. The process of the present invention is characterized by the coupling of the diazo with an excess coupler at a temperature of 0-10 ° C, preferably about 5 ° C. The resulting suspension is then heated with ethoxylated alkylphenol in the presence of a strong alkali to provide an opaque, strong and easily dispersible product. After the addition of the alkali and the surfactant, the dye suspension is heated to 0-100 ° C, preferably between 95-100 ° C. The duration of the heating depends on the suitable particle size required. In general, a prolonged heating produces more dye and more opaque.

The dyes of the invention exhibit very good dyeing power and can be easily dispersed. They are suitable for plastics, printing inks, coating applications and paints such as, for example, solvent-based, water-based and enamel-based paints. The dyes of the present invention are further illustrated by the following non-limiting examples in which all portions and percentages are by weight, unless otherwise indicated.

Example 1 A diazo solution was prepared by adding para-chloro-ortho-nitroaniline (430 grams) and concentrated hydrochloric acid (1100 grams) to water (9000 ml). The mixture was cooled to 0-5 ° C and the amine was diazotized by adding a mixture of sodium nitrite (192 grams) and water (600 grams). The mixture was stirred for three hours. A sulfamic acid solution was added to remove excess nitrite and then charcoal (3 grams) and celite (3 grams) were added and mixed for 15 minutes. The resulting diazo solution was clarified. A coupling solution was prepared by dissolving 5-acetoacetylamino-benzimidazolone (610 grams) in a solution containing water (20,000 ml) and sodium hydroxide (1200 grams). Charcoal (9 grams) and celite (6 grams) were added and stirred for one hour, then clarified. Sodium hydroxide (194 grams) and acetic acid (1450 grams, 56%) were added and the pH adjusted to 6.0. The resulting coupling solution was cooled to 5-8 ° C. The diazo solution was added to the coupling solution over a period of 1.5 hours resulting in a dye suspension that was stirred for one hour. Sodium hydroxide (290 grams) was added and the mixture was heated to 95-100 ° C and maintained for 15 minutes. Nonylphenoxy poly (ethyleneoxy) ethanol was added (61 grams) and additional sodium hydroxide (194 grams) and the temperature was maintained at 95-100 ° C for 6 hours. The mixture was cooled to 70 ° C and filtered to obtain a dye in presscake. The press cake was heated with water to lower conductivity and dried, providing an orange colored dye with excellent light fastness and weathering, high coating power, good dispersion capacity and high gloss.

Example 2 The dye of Example 1 was mixed in an acrylic enamel paint with the components shown in the following Table 1.

Table 1 (a) - the dye of Example 1 and also the conventional dye Sunfast 271-9136, manufactured by Sun Chemical, Ft. Lee, 'NJ.

The acrylic enamel paints were compared and measured using a Spectraflash SF600 Plus equipped with Colortools QC, version 3.0, manufactured by Datacolor International of Applied Systems, Inc., Charlotte, NC. The results are shown in the following Table 2.

Table 2 The acrylic enamel paint that contained more of the dye prepared according to the present invention was more opaque in dye by dough against the conventional dye.

Example 3 A diazo solution prepared according to Example 1 was added over a period of 1.5 hours to a solution of the coupling prepared according to Example 1 and the resulting suspension was stirred for one hour. Sodium hydroxide (484 grams) was added and the mixture was heated to 95-100 ° C and maintained for 15 minutes. Nonylphenoxy poly (ethyleneoxy) ethanol (61 grams) was added and the temperature of the mixture was maintained at 95-100 ° C for another 6 hours. The mixture was cooled to 70 ° C and filtered to obtain a dye in press cake. The press cake was heated with water to a lower conductivity and dried, providing an orange colorant with excellent light fastness and weathering, high covering power, good dispersion and high brightness.

Example 4 The dye of Example 3 was mixed in a 50:50 dye and an acrylic enamel paint with 95: 5 dye using the same components and percentages by weight as shown in Example 2 (Table 1). The acrylic enamel paints were compared and measured according to the method of Example 2. The results are shown in the following Table 3.

Table 3 The acrylic enamel paint which contained more of the dye prepared according to the present invention was more opaque in dye by dough and had a greater tinting power than that contained in the conventional dye.

Example 5 A diazo solution was prepared by adding para-nitroaniline (109.2 grams) and concentrated hydrochloric acid (266.8 grams) to water (2400 ml). The mixture was cooled to 0-2 ° C and then diazetized by adding a mixture of sodium nitrite (51 grams) and water (100 grams). The mixture was stirred for two hours. A solution of sulfamic acid was added to remove excess nitrite and then charcoal (1 gram) and celite (1 gram) were added and stirred for 20 minutes. The resulting diazo solution was clarified. A coupling solution was prepared by dissolving 5-acetoacetylamino-benzimidazolone (155 grams) in a solution containing water (5100 ml) and sodium hydroxide (76 grams). Charcoal (1 gram) and celite (1 gram) were added and then clarified. Sodium hydroxide (101 grams) and acetic acid (200 grams, 70%) were added and the resulting coupling solution was cooled to 5 ° C. The diazo solution was added to the coupling solution over a period of 1.5 hours resulting in a dye suspension that was stirred for 30 minutes. The pH of the coloring suspension was adjusted to 8.0 with a diluted sodium hydroxide solution (25%). The color suspension was heated to 95-100 ° C and maintained for 15 minutes. Sodium hydroxide (39 grams) and nonylphenoxy poly (ethyleneoxy) ethanol (8 grams) were added and the temperature was maintained at 95-100 ° C for 6 hours. The mixture was cooled to 70 ° C and filtered to obtain a dye in presscake.

The press cake was washed with water at lower conductivity and dried, providing an orange dye with excellent lightfastness and weathering, high covering power, good brightness distribution and high capacity.

Example 6 The dye of Example 5 was mixed in an acrylic enamel paint of the components shown in the following Table 5.

Table 5 (b) - the dye of Example 1 and also the conventional dye Clariant H5G-70, manufactured by Clariant, Coventry, Rl.

The acrylic enamel paints were compared and measured according to the method of Example 2 and the results are shown in the following Table 6.

Table 6 The acrylic enamel paint which contained more of the colorant prepared according to the present invention was more opaque in the nuance by mass and had a greater tinting power than that contained in a conventional dye. The invention has been described in terms of the preferred embodiments thereof, although it can be applied more broadly as will be understood by those skilled in the art. The scope of the invention is limited only by the following claims.

Claims

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A process for conditioning an organic azo-dye characterized in that it comprises: (a) prepare one. aqueous suspension in an azo dye in the presence of a surfactant of ethoxylated alkylphenols and an alkali; and (b) heating the suspension to a temperature above about 70 ° C resulting in a conditioned organic azo-dye. The process according to claim 1, characterized in that the step of preparing the aqueous suspension comprises the steps of: (a) coupling a diazo with an excess coupler at a temperature of at least about 0-10 ° C to form a suspension of azo-dyes; (b) adding an alkali to the coloring suspension; (c) heating the suspension and the alkali to a temperature above about 70 ° C; and (d) adding additional alkali and an ethoxylated alkylphenol surfactant to the suspension. 3. The process according to claim 1, characterized in that the azo-dye is selected from the group consisting of naphthol reds, monoazo yellows, monoazo oranges, yellow diarylurides and diaryluro oranges. The process according to claim 1, characterized in that the surfactant is selected from the group consisting of nonylphenoxy poly (ethyleneoxy) ethanols and octylphenoxy poly (ethyleneoxy) ethanols. The process according to claim 1, characterized in that the surfactant is between approximately 2% by weight and 12% by weight of the colorant. The process according to claim 5, characterized in that the surfactant is between approximately 3% by weight and 10% by weight of the colorant. The process according to claim 1, characterized in that the alkali is selected from the group consisting of sodium hydroxides, potassium hydroxides, lithium hydroxides and ammonium hydroxides. The process according to claim 1, characterized in that the amount of alkali is at least about 2 mol equivalents of alkali per mole of azo-dye. The process according to claim 8, characterized in that the amount of alkali is at least about 2 to about 10 mol equivalents of alkali per mole of azo-dye. The process according to claim 9, characterized in that the amount of alkali is at least about 4 to about 6 mol equivalents of alkali per mole of azo-dye. The process according to claim 1, characterized in that the heating step is carried out at a temperature above 80 ° C. 12. The process according to claim 11, characterized in that the step of heating is carried out at a temperature between approximately 90 ° to 100 ° C. The process - according to claim 12, characterized in that the heating step is carried out at a temperature between about 95 ° C to 100 ° C. The process according to claim 1, characterized in that the dye is monoazo yellow and the amount of surfactant is about 6% by weight of the dye. 15. The process according to claim 1, characterized in that the dye is naphthol red and the amount of surfactant is about 10% by weight of the dye. 16. Azo-dye conditioned by the process according to claim 1. 17. A printing ink comprising an azo-dye conditioned by the process according to claim 1. 18. A coating comprising azo-dye conditioned by the process according to claim 1. 19. The coating according to claim 18, characterized in that the coating is selected from the group consisting of solvent-based paints, water-based paints, and enamel-based paints. 20. The coating according to claim 19, characterized in that the coating is a paint with enamel base.